In telecommunications, presence information has traditionally been used to indicate the ability, availability and willingness of a person to communicate. More generally, a person's presence information provides contextual information to let others know something about the present context of the person.
Presence is currently one of the key drivers behind instant messaging (IM) and some of the recent developments in VoIP technology, in particular Session Initiation Protocol (SIP). While these and other rudimentary presence technologies have been implemented and discussed (see, e.g., the IETF's RFC 2778 entitled “A Model for Presence and Instant Messaging” and RFC 4480 entitled “RPID: Rich Presence Extensions to the Presence Information Data Format (PIDF)”), these technologies are still generally quite embryonic. These prior-art technologies provide limited flexibility, scalability, security and privacy. Accordingly, improvements in the manner in which presence information is collected, managed and disseminated remain highly desirable.
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.